/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.formats.avro;

import org.apache.flink.api.common.serialization.BulkWriter;
import org.apache.flink.core.fs.FSDataOutputStream;

import org.apache.avro.file.DataFileWriter;

import java.io.IOException;
import java.io.OutputStream;

/**
 * A factory that creates an {@link AvroBulkWriter}. The factory takes a user-supplied
 * builder to assemble Parquet's writer and then turns it into a Flink {@code BulkWriter}.
 *
 * @param <T> The type of record to write.
 */
public class AvroWriterFactory<T> implements BulkWriter.Factory<T> {
	private static final long serialVersionUID = 1L;

	/** The builder to construct the Avro {@link DataFileWriter}. */
	private final AvroBuilder<T> avroBuilder;

	/**
	 * Creates a new AvroWriterFactory using the given builder to assemble the
	 * ParquetWriter.
	 */
	public AvroWriterFactory(AvroBuilder<T> avroBuilder) {
		this.avroBuilder = avroBuilder;
	}

	@Override
	public BulkWriter<T> create(FSDataOutputStream out) throws IOException {
		return new AvroBulkWriter<>(avroBuilder.createWriter(new CloseShieldOutputStream(out)));
	}

	/**
	 * Proxy output stream that prevents the underlying output stream from being closed.
	 */
	private static class CloseShieldOutputStream extends OutputStream {
		private final OutputStream out;

		public CloseShieldOutputStream(OutputStream out) {
			this.out = out;
		}

		@Override
		public void write(int b) throws IOException {
			out.write(b);
		}

		@Override
		public void write(byte[] buffer) throws IOException {
			out.write(buffer);
		}

		@Override
		public void write(byte[] buffer, int off, int len) throws IOException {
			out.write(buffer, off, len);
		}

		@Override
		public void flush() throws IOException {
			out.flush();
		}

		@Override
		public void close() throws IOException {
			// we do not actually close the internal stream here to prevent that the finishing
			// of the Avro Writer closes the target output stream.
		}
	}
}
